Residential, commercial and industrial establishments are typically provided with meters for measuring consumption of commodities, including electricity, gas and water, and other services, supplied to a building by utilities. For example, an electricity provider typically provides each consumer's premises with a conventional electricity meter having a rotating disc and counter to measure and indicate cumulative usage in kilowatt hours (kWh), as a measure of usage or consumption of electrical energy for billing the consumer. Similar meters may be provided for gas, water or other services/supplies.
More recently, many utility companies and government agencies have been installing “smart meters” which can record cumulative or total energy usage and transmit the data to a central location, avoiding the need to employ a fleet of meter readers to take meter readings. Smart metering systems also facilitate data collection in terms of speed, accuracy and total cost of collection. Moreover, smart metering allows for more detailed monitoring of time of use, cost and other data. Most smart meters are configured to monitor usage and apply different rates or tariffs for energy usage based on a current rate period or time of use period. Typical resolution of time measurement is 15 minute or 60 minute intervals. A number of different rate periods and corresponding rates may be established based on time of day (e.g. peak rates and off-peak rates), day of the week, month, season, varying cost of supply or other factors. Other utilities set tiered rates based on consumption levels. Thus utilities and local distribution companies can set different tariffs for usage depending on a rate period. Consumers may regulate their consumption accordingly, for example by deferring use to a lower cost, off peak rate period.
Introduction of smart metering by utility companies and service providers is driven in part by the need to encourage reduced consumption during peak hours, and typically several tariffs are provided dependent on time of use (e.g. peak/off-peak) to provide a cost incentive for off peak use, or energy conservation during peak periods. For electricity generation, off-peak use spreads demand on the system for improved power management at peak demand, which is particularly important in climates placing extreme demands on provisioning for peak periods (heating during winter months and cooling during summer months).
Nevertheless, even with smart metering, the consumer may not receive information on consumption and cost from the utility provider until a billing is received. Furthermore, since conventional and smart meters are typically located on the outside of a building, consumers need more convenient ways to monitor current consumption and cost in real-time, for example from within the home.
Smart meter systems are typically networked, through wired or wireless networks, to provide for remote monitoring and meter reading by utility/service providers. Consequently, there are a number of known systems for providing consumers with information on their usage, for example in-home or on-premises displays which may be linked to the smart meter using wireless or wired connections. Smart meters may communicate with other devices such as remote appliance controllers (RACs), programmable communicating thermostats (PCTs) and in-home displays (IHD) for energy management etc. These in-home or in-building displays typically have a digital display to indicate usage information, such as consumption, and may provide for simple graphical representations of information, indicator lights and audible warnings.
Wirelessly-enabled smart metering and monitoring systems may rely on a number of known wireless networking, or mesh and sensor networking protocols depending on range of transmission and security requirements (e.g. based on IEEE 802.15.4, ANSI C12.19, C12.22, Zigbee).
Where smart meters are not installed, several retrofit solutions may be offered for automatically reading data from conventional meters and transmitting data wirelessly or through wired network connections.
For example, the “Power cost” monitor by Blue Line Innovations, described in US published patent application No. 2005/0222784 (now U.S. Pat. No. 7,174,260), provides a digital display capable of displaying several parameters and graphically representing data in real time relating to energy usage and cost, together with related information such as outside temperature. This monitor includes a numeric display, with a graphical display of a spinning wheel to indicate power consumption rate (disk emulator). In this example, in-home units may communicate with a sensor device attached to the exterior of a conventional electricity meter which senses the rotation of the wheel and communicates the information to the in-home monitor by way of a wireless link.
Where smart metering is available, there are a number of digital displays available to consumers for displaying numeric and simple graphical information. These may be wall-mounted like a wall thermostat, or plug-in to an electrical wall outlet, and may receive information from a meter system through wired or wireless connections.
Other examples of electrical power usage monitors are: the Ritetemp universal wireless thermostat by Golden Power Manufacturing, which includes coloured light utility rate indicators; Ambient digital graphical displays, which include the Energy Joule display which plugs into an electricity outlet and provides available displays coloured backlighting depending on rate; other displays also provide related weather and temperature information. Another plug-in unit marketed as Powerstat by TWACS by DCSI provides audible and visual alerts; Powerwatch provides secure wireless monitoring with data feed to a watch-type monitor worn on the wrist.
Another manufacturer, EcoMeter manufactures display units with digital graphical displays, for monitoring both energy and water usage; a set of LEDs along the bottom of the screen indicate tariff periods by colours: green for off-peak; yellow for shoulder tariff; orange for peak tariff; red for dynamic peak tariff/high demand. This device also translates energy usage to greenhouse gas emissions equivalents.
Although a number of in-home (in-building, on-premises) displays are available, existing products have some limitations, and may not be compatible with known smart metering systems. Some of the units require a consumer to be aware of any changes in status, and be close enough to read and interpret data on the display. Furthermore, where units plug into an electrical wall outlet, there are limitations on placement and the device may not be conveniently located for reading of a digital display.
Some users also want to know their current energy usage, either in terms of current cost (in a currency unit, such as dollars or cents) or in units of measurement of energy (such as kilowatt hours). Some smart meters may not provide information on rate period, and even when information is available, consumers may not be able to immediately interpret numeric data without analysis because there are several types of billing: e.g. single flat rate mode; tiered rate mode; time-of-use rate modes.
As mentioned above, some approaches exist to transmit energy usage data from a smart meter to a central station, or possibly even to a location within a building, for reading by a user. When smart meters are not installed, such approaches often require an electrician to install specialized equipment connected to a conventional meter, and the equipment generally requires a separate power supply or power source.
Increasing energy and fuel and other costs, and concern for the environmental impact of energy and resource demands, provide incentives for smart metering of utilities providing improved monitoring of usage, time of use dependent rates, and feedback to the both the utility company and consumers.
It is understood that the success of such smart meter initiatives largely depends on the extent to which energy consumers, such as electricity consumers, are able to use smart metering to take advantage of opportunities for conservation and better manage their consumption and, as a result, their energy costs.
It is, therefore, desirable to provide an apparatus that can provide an indication of current energy usage with respect to a provided service, such as electricity, in relation to an applicable rate period. To encourage reduced demand at peak periods, and conservation, there is a need for improved devices that are relatively inexpensive yet provide consumers with a convenient, visual indication of current (real-time) usage in terms of cost and consumption for electricity usage and usage of other services.
Other aspects and features of the invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.